Karen at Books on the Knob has noted that HarperCollins has put hundreds of their e-book titles on sale at $0.99 each. They also seem to be on sale at B&N, but of course there doesn't seem to be any mention of it, nor a page you can go to for a list of them.

Doug, thanks for posting this! I had just bought 13 books from Amazon to read using my Kindle app, but as soon as I saw your post, I went back to Amazon, where I was able to return them all for a refund. Now I have bought them all at B&N to read on my (much easier to read) NOOK.